Electric circuit breaker



Aug. 24, 1943. c. BRESSON ELECTRIC CIRCU IT BREAKER 5 Sheets-Sheet 1 Filed Aug. 15, 1939 Aug. 24, 1943. c. BRESSON ELECTRIC CIRCUIT BREAKER Filed Aug. 15, 1939 5 Sheets-Sheet 2 Aug. 1943- c. BRESSON ELECTRIC CIRCUIT BREAKER Filed Aug. 15, 1939 5 Sheets-Sheet 3 7//////// /////////////////////7///////// -W// ////Y// w-wA// W im zg/gz Aug. 24, 1943. c. BRESSON ELECTRIC CIRCUIT BREAKER 5 Sheets-Sheet 4 Filed Aug. 15, 1959 .F l-\ Ewan Y x M r 5.

Aug. 24, 1943. I c. BRESSON ELECTRIC CIRCUIT BREAKER Filed Aug. 15, 1939 5 SheetsSheet 5 P z 1 h M 2 "2 T 1 1 3 I I I I F. 9

IT x z'xi P Patented Aug. 24, 1943 7 2 327 493 UNITED STATES PATENT OFFICE EIECTRIC C IRCU IT BREAKER Charles Bresson, Lyon, France; vested in the Alien Property Custodian Application August 15, 1939, Serial No. 290,241 In France August 31, 1938 14 Claims. (Cl. 175-294) This invention relates to electric circuit breaksame parts in the position they occupy on terers. mination of the circuit closing operation.

One of the objects of the invention is to pro- Referring to Fig. 1, the main circuit breaker vide electric circuit breaker apparatus having A and the auxiliary circuit breaker B are conprovision for the ultra-rapid reclosure of the cir- 5 nected to the circuit of the system or line to be.

cult, for use with either single or. polyphase elecprotected by suitable conductors en and em retric plants or circuits. spectively and to each other by a suitable device Another object of the invention is to provide S, said main circuit breaker A being controlled electric circuit breaker apparatus having proviby suitable protecting relays and operated by sion for the ultra-rapid reclosure of the circuit, suitable operating means actuated electrically for use with either single or polyphase electric y stored p mechanical pneumatic y. plants, said apparatus comprising a main circuit ei af r o e ul y t t breaker of delayed operation, connected in series Said auxiliary circuit breaker B, which may with an auxiliary circuit breaker whi h, upon connected (electrically) to and disconnected th occurrence of any fault in any one or 1h from said main circuit breaker A by said device several of the phases, operates immediately to is of a Single uni-Polar wntlolled yp each break the circuit of the phase or phases affected of its poles being controlled y p t and then to reclose said circuit, before said main pid tin ay a p at d by an d circuit breaker has had time to operate to break Pendent Pneumatic Operating m ch nism. Its said ir it electric plant may be of the same type and use The invention, and th a d h other the same volume of oil as an ordinary circuit jects of the invention as shall hereinafter appear, breaker, it differing from h latter O y 1118- will be readily nd r t from t u m chanically; the difierences will be hereinafter description, taken in connection with the acfully set forth. companyin drawi of embodiments of the The pneumatic actuating means of the arc Vention herein given for n t t purposes, drawing contacts of the auxiliary circuit breaker the true scope of the invention being more paraqtuates Said contacts through mechanism ticularly pointed out in the appended claims which is illustrated in a general manner in Fig. 2.

In the drawings: Referring to said Fig. 2, said pneumatic actuat- Fig. 1 is a view in elevation of a single phase mg means is diagrammatically indicated t 1 element of the main circuit breaker A and a sinand Operates Said contacts by means of a rotary ale phase element of the auxiliary circuit break- Post Co of insulating material, and a System of er B, b th mounted upon a carriage o and a levers, cranks and ball-jointed links. The parts d i for connecting and disconnecting A and of this mechanism are always connected, whether Fi 2 shows diagrammatically mechanism by the circuit to be protected be closed or opened hi t pneumatic operating means f Said by the circuit breaker B. Means are provided element 3 operates t tt to damp each movement of this mechanism at its Fig. 3 Shows diagrammatically the mechanical conclusion, said means herein illustratively comand electrical structure of the pneumatic operprising two Shock absorbers amlon the movable ating means of element B. contact and mm on said post Co, and the pneu- Figs 4 and 5 Show details of the pneumatic matic operating means also contributes to the operating mechanism of element B. dafnpmg actionsaid damping means enables Fig 6 Shows partly diagrammatically a com said post to be moved very rapidly without risk of breaking it, althou h it f structmn m Wmch the pneumatlc Operating is of importance as ripidit 8f t i o n i s a i means for the element B is in proximity to the portant feature of this mechanismarc-drawing contacts of the latter this Fig. 6 Ref erring to Fig. 3, which illustrate d am- Shows dlagnfmmatlcany the electncactuat' matically the mechanical and electric: opz ting m means Sa d pneumatic means. mechanism of the pneumatic operating means,

Fig. 7 is a detail Of a pa Of On an said pneumatic means comprises a reservoir R larged scale, and Fig. 7a is a detail of Fig. 'I. for compressed fluid, air for example, from which Fig. 8 is a further detail of Fig. 6 showing the it passes through a valve Va to a cylinder Po position of the parts on termination of the circuit through a distributor d1 which directs it alterbreaking operation, also on an enlarged scale. nately upon the one or the other side of a piston Fig. 9, on the same scale as Fig. 8, shows the P1 in said cylinder. The movement is transmitpost Co. Operation of said piston P1 is started by the opening of said valve Va by operation of a rapid acting circuit-breaking means, a solenoid Bd for example, the core of which engages lever l and causes the latter to actuate member 8 to open valve Va. At the start of the rotary move ment of said post Go, a cam Ca carried by the latter engages a roller on a pusher p, which engages said lever to hold said valve Va open.

- reclosed by an adjustable spring R1, but a suitable time lag delays such closure for a time (several seconds for example) suificient to prevent a second breaking of the circuit of the system by said auxiliary circuit breaker B, should the fault persist. Any suitable time lag device may be used in accordance with my invention, said device herein conveniently consisting of a suitable weight M carried by said lever L3 and adapted to act in opposition to said. spring R1.

In case of a fault on said system, a current transformer Ti the primary of which is inthe circuit to be protected, actuates an ultra-rapid operating relay RU which closes a break cm: in the circuit of another ultra-rapid operating relay CR, which in turn closes a break CR in the circuit of said solenoid Bd, thus causing the latter to operate valve Va, piston P1 and post 00 to 0perate said auxiliary circuit breaker B to break the circuit of the system to be protected. This closure of said break CR0 simultaneously closes the circuit of an electro-magnet E of a time lag device serving to close the circuit of a solenoid B'd and eiTect a delayed operation of said main circuit breaker A to break said circuit of said system to be protected should said fault persist. Said time lag device may conveniently comprise a weight M, an adjustable spring R and a movable stop Bu carried by the core of said magnet E.

When the auxiliary circuit breaker B breaks the circuit of said system to be protected, the

post Co in its further rotation cuts the current 50 of said magnet or solenoid E at contacts CT1 and said stop Bu drops to prevent closure of the circuit of said solenoid or magnet B'd. Upon reclosure of the circuit of said system by said auxiliary circuit breaker B, should the fault still persist, the circuit of electro-magnet B'd will be closed at C by the operation of RU, CR and E in the continued rotation of Co.

The core of magnet B'd acts upon the free end of latch-lever L4 (Fig. 3), pivoted at L40, and the main circuit breaker A breaks the circuit of said system, cutting at CT; the circuit of electro-magnet E, causing Bu to drop and open contacts 0', and also cutting at CTz the circuit of B'd.

On the other hand, in the case of a simple excess of intensity, rendering the operation of auxiliary circuit breaker B useless, the circuit of electro-magnet Bd may be closed directly by any conventional relay RS, the operation of which is retarded by several seconds.

Fig. 4 shows in detail the pneumatic part of the operating mechanism of the auxiliary circuit breaker B in the position they occupy when the contacts of said circuit breaker are in closed position. Movement of piston P1 is transmitted to 75 opened.

ted by a link B1 and crank M1 to said rotary M1. The angle of rotation of said post for the circuit breaking and the circuit closing operations is 60 for each. Distribution of the compressed 5 air is effected by a slide-valve gearcomprising pistons P2 and P3, rigidly connected to each other by a rod pivoted at its free end to a beam Ba. Upon breaking of the circuit by said circuit breaker B, compressed air is admitted upon the left side of piston P1 (see arrow F2) ofcylinder Po, and the exhaust is opened at the other side of said piston (see arrow F3) On termination of the circuit breaking action of said circuit breaker B the operation of said slide-valve is reversed, thus causing the reclosing of the circuit by said circuit breaker. Furthermore, as the time elapsing between the termination of the circuit breaking operation of said circuit breaker and the starting of the cir- 2 cuit closing operation thereof should be adjustable, said reversed operation of said slide-valve.

is divided into two periods; the first period lasts .during the entire circuit breaking operation of said circuit breaker; the crank M1, by means of the link B2, swings beam Ba about its fulcrum O1, which is held fixed by the joint action of link B3, crank M2 and locking engagement with the latter of the shorter arm of two armed lever L at A1. Beam Ba and pistons P2 and P3 move from position 0 to position 1; that is to say both the admission of compressed air to and its exhaust from cylinder P0 are cut ofi at the end of the circuit breaking operation of said circuit breaker. The second period is that of the circuit reclosing operation of said circuit breaker, by movement of said beam Ba and said pistons P2 and P: from position 1 to position 2, thus tensioning driving spring R1. This movement is eifected automatically by piston P4 responsive to air pres- 40 sure, intake valve Va having been held open by cam Ca acting on lever I when latch-lever L releases crank M2. It is the adjustable retardation of the release of said crank M2 by said latch-lever L which efiects the desired delay of the circuit reclosing operation of said circuit breaker. Any suitable means may be provided to efiect said delay in accordance with my invention, the illustrative device herein used for that purpose comprising a dash-pot V0, the piston 'rod of which is adapted to co-operate with said lever L, said dash-pot communicating with said valve Va by a passage V01 provided with a screw controlled vent vi for regulating the degree of retardation. Operation of said circuit breaker to reclose the circuit takes place immediately upon the release of said crank by said latch-lever L, said link B2 thus returning said beam Ba to position 3 by swinging it about its fulcrum O1, shifted to 02 and there held by piston P4 and the compressed air behind the latter. In this position, pistons P2 and P3 have been returned to their position v1, both the intake and the exhaust of said valve gear being closed. Upon termination of the circuit reclosing operation of said circuit breaker, as piston P4 is held in place by the air pressure, spring R also remains under tension and the apparatus comes to rest. It is only upon closure of intake valve Va that the pressure behind piston P4 drops and that spring R1 returns pistons P2 and P3 to the position 0. The supply of air being thus cut off,

said circuit breaker does not operate to break the circuit. The apparatus is thus ready to function again, and the circuit breaker will operate to break the circuit so soon as the intake valve is the rotary post Go through link B1 and crank accuse AS shown in Fig. 5, the circuit breaker B may be locked in its position in which the circuit is closed, by causing direct'engagement of roller on free end of lever L1 with free end of crank M1. As the release of said crank is to take place so soon as the intake valve is opened, such release may be toggle and permits said crank to be locked again when said circuit breaker has reclosed the circuit.

The pneumatic operating mechanism of circuit breaker B may be located in proximity to the arc-drawing contacts of the latter. The compressed air will then be conveyed to said operating mechanism through an insulating column I. Fig. 6 shows such an arrangement and also the electric actuating mechanism of said pneumatic operating mechanism, said auxiliary circult breaker B being shown partially in section. Its movable contact C, which enters the circuit breaking chamber D, is moved by a lever L1 connected to piston P1 of said pneumatic mechanism by a link B1. Slide valves T1 and T2 of a slide valve gear admit compressed air at one or the other side of said piston P1. Air is supplied to said slide valve gear through a controlling valve S which communicates through said hollow column I of insulating material with a compressed air reservoir Ra located at the base of said circuit breaker. Valve S is opened by slight rotary movement of said column I communicated thereto by a, piston P2, both ends of said column being connected to fixed parts of the tubular system by flexible tubular connections F1 and F2. To cause said circuit breaker to break the circuit, compressed air is admitted behind piston P2 which thus, through suitable connections, turns said column I through a slight angle, say about The upper nose N of said column in rotating first executes a slight lost motion and then engages a pawl M (see Fig. 7) which swings lever X downwardly about its fixed fulcrum O1 to open valve S. Said nose then automatically disengages said pawl when the latter strikes a fixed stop 2 (see Fig. 8). See page 4 for detailed description.

Opening of valve S admits compressed air under piston P1 at 111 (see Figs. 8 and 9). Said piston rising causes said circuit breaker B to break the circuit. Cam X acting upon roller G keeps valve S open during practically the entire stroke of piston P1. 7

During the operation admission of air at an and exhaust of air at (12 is gradually cut off by slide valves T1 and T2 operated by beam U which is connected to lever L1 by a link B2 so that movement of said parts is damped. At the end of the circuit breaking operation of said circuit breaker B the different parts occupy the positions shown in Fig. 8.

Closure of the circuit by said circuit breaker B is effected by admission of compressed air at (12. After a certain lapse of time, which can be regulated and is determined by inflation of. a

' retarding device R, lever L2 releases beam U,

which is then swung upwardly by piston P3 behind which the air is compressed. Slide valves T1 and T2 uncover ports (11 and oz and compressed air is admitted through or behind piston P1 and exhausted through port or, whereupon the various parts at the conclusion of their movements assume the positions shown in Fig. 9.

During the operation admission port a2 and exhaust, port on are gradually closed by slide valves T1 and T2 which are moved downwardly by link B2. The downward stroke of beam U is limited by the compressed air behind pistons P: which prevent said piston from descending further, and ports (11 and a: are kept closed.

When roller G has been returned to its initial position (see Fig. 'l) valve S is released and spring 11 returns it to its seat. Compressed air behind piston P3 can now escape through the small vent Z1 of said valve S. The pressure now diminishes and piston P3 is drawn downwardly by spring 12, thus swinging beam U downwardly; slide valves Tl and T2 uncover ports a1 and a2 and the retarding or time lag device R is deflated. When the pressure is sufiiclently reduced, lever L2 is returned to its initial position by spring r3, thus locking the left end of beam U.

A further cycle of operations is prepared at the upper portion of the apparatus (Fig. 6).

The column I is not returned to its initial position until this cycle of operations is completed. Spring T t initiates the operation so soon as the pressure behind piston P2 is sufiiciently reduced. The period of time which elapses before this reduction in pressure occurs is determined by the size of a vent as, said size being regulated or adjusted once for all.

Upon the occurrence of a fault, a current transformer Ti (Fig. 6) actuates an ultra rapid relay RU to close the circuit of a contact device CR the operation .of which is also rapid. Said c0ntact device in turn closes the winding Bd of an electro-magnet Ev, which engages a stud S and opens valve V0,. thus admitting compressed air from reservoir Ra to cylinder Rt on left side of piston P: which moves to the right against the action of spring r4 and, through a suitable connection with insulating column I rotates the latter about its axis to break a contact GT3, thus de-energizing Winding Bd. On the other hand in this rotary movement said column closes contact GT1, thus energizing electro-magnet E of a time lag M. umn I also actuates the operating mechanism of said circuit breaker causing the latter first to break the circuit and then to reclose it, thus effecting a complete cycle.

Upon reclosurc of the circuit by said circuit breaker, if the fault no longer exists, the contacting device CR is no longer attracted and the circuit of the circuit breaking winding or coil 'Bd of the triple pole circuit breaker A will not be closed. Column 1 will return to its initial position shown in Fig. 6 only after a certain lapse of time following closure of the circuit by the circuit breaker as above stated.

Should the fault persist after reclosure of the circuit by said circuit breaker, the relay EU will again close the circuit of said contact device CR which now no longer supply current to said Winding Ed, the latters circuit being open at CTs, out supplies winding Bd which controls the circult breaking operation of said triple pole cir cult breaker A. The time lag device M, the lag of which is of less duration than the time the ultra rapid circuit breaker B takes to operate to close the. circuit, has prepared the closure of the circuit of Bd said device M having been supplied with current ever since the beginning of the rotary movement of said insulated column its rotary movement said (201- 1 I. Said circuit breaker B has thus remained in circuit-closing position, and the main circuit breaker A is in the position in which the circuit is broken.

In short should a fault persist the circuit of the winding B'd of the electrically controlled valve Ev remains open at CT: so long as column I has not returned to its original position, that is to say for a period of time sumciently long for the main circuit breaker A to break the circuit.

On the other hand in asimple case of excess intensity, rendering unnecessary the operation of the auxiliary circuit breaker B to close the circuit, the current of the winding B'd may be closed directly, for example, by a relay RS the operation of which is retarded for several seconds.

Operation of ,the apparatus described is as follows: If a fault occurs which for example affects one phase of a line provided at its ends with circuit breaking groups of'the kind shown in Fig. 1, each comprising apparatus A and B, the ultra rapid operating relays RU (Figs. 3 and 6) of the apparatus B immediately operate to cause said apparatus B to break the current of the line; then, afterthe lapse of a certain time from the actuation of said relays, predetermined by adjustment, .the two apparatus B are operated in respect to said phase, at both ends of the line to close the current of the line. It now the fault no longer exists, the service of the line is reestablished without the two main circuit breakers A having been operated by their time lag relays to break the line. If on the other hand the fault still persists, the.time lag relays of the two main circuit breakers A (MR', Fig. 3 and M Fig. 6) act to cause said main circuit breakers A to break the current at the three poles thereof and to disconnect the device S (see Fi 1) while the current remains closed at the three poles of the auxiliary circuit breakers B.

The invention possesses the following advantages among others. All voluntary operations such as breaking and closing of the circuit with a or without synchronisation are effected by normal circuit breakers A, the ultra rapid circuit re-closing apparatus B remaining in circuit closmg position, that is to say always ready to operate to break the circuit on occurrence of a fault.

Should a fault persist the two consequent interruptions of the circuit are effected in two absolutely distinct, separate chambers, so that absolute safety is assured. The pressures engendered in the chambers in which the circuit is broken are weaker, and in the case of the second break there is a total absence of gas that could break, so that re-striking of the arc is impossible.

, The electric installation of a circuit breaker A may be used in the auxiliary circuit breaker B with the ultra rapid reclosing of the circuit, so that the same'parts are interchangeable.

Said auxiliary circuit breaker B can be applied to all types of circuit breakers in use, by simple juxtaposition.

Finally the periods of time elapsing between the breaking of the circuit and its reclosing by apparatus B can be regulated or adjusted within wide limits.

I am aware that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and I therefore desire the present embodiments to be considered in all respects as illushave been ionized on the occurrence of the first aaaaaas trative and not restrictive, reference being had to the appended claims rather than to the foregoing description to indicate the scope of the invention.

Referring to Figs. 7 and 7a, the axis 02 about which said nose N rotates being in a difierent vertical plane from that of said nose, the latter, in its swinging movement, as it approaches the arm m3 of pawl M moves substantially in the plane of said arm, and engages the end of the latter. said nose thus pushes said pawl to the right (see Fig. 7) and the latter, being carried by cam X and having its arm mi in engagement with stop Z1 on said cam X, swings the latter contraclockwise about its pivot 01 to cause its free end to push downwardly upon valve stem 21 of valve S and opens, the latter. This operation also swings lever L1 to cause roller G on the latter to engage the upper cam surface of said 1 cam X. 1 This tends to turn pawl M clockwise by reason of the engagement of said arm 7m with said stop Z1. Meanwhile nose N in its further rotation causes lower arm m2 of said pawl to engage stop 2. This combined with the action of stop Z1 and that of nose N, causes arm ms of said pawl to become disengaged from said nose N, and said pawl returns to the position shown in Fig. 8.

I claim:

1. The combination of a main circuit breaker comprising at least one pole; a circuit to carry a load and controlled by said main circuit breaker;

an auxiliary circuit breaker comprising the same.

number of poles as said main circuit breaker, connected in series with the latter; means for ensuring at will the simultaneous closing or opening of the arc-drawing contacts of all of the poles of said main circuit breaker, the arc-drawing contacts of said auxiliary circuit breaker remaining closed; means, operative in case of an abnormal current in said circuit, to open the arcdrawing contacts of the pole of said auxiliary circuit breaker that is traversed by said abnormal current and then to reclose said contacts after a very short interval; and means rendered operative thereafter, if said abnormal current persists, to open the arc-drawing contacts of said main circuit breaker, the arc-drawing contacts of said auxiliary circuit breaker remaining closed.

2. The combination of a main circuit breaker comprising at least one pole; a circuit to carry a load and controlled by said main circuit breaker; an auxiliary circuit breaker comprising the same number of poles as said main circuit breaker and connected in series with the latter; operating means including an ultra-rapid relay in the controlling circuit of each of the poles of said auxiliary circuit breaker and rendered operative in case of an abnormal current in said first mentioned circuit for carrying a load, to open the arc-drawing contacts of that pole of said auxiliary circuitbreaker that is traversed bysaid abnormal current and then to reclose said contacts after a very short interval; and means rendered operative thereafter, if said abnormal current persists, to open the arc-drawing contacts of said main circuit breaker, the arc-drawing con- 'erative in case of an ating means including an the controlling circuit of said auxiliary circuit ultra-rapid relay in each of the poles of breaker and rendered opabnormal current in said first mentioned circuit, for carrying a load, to open the arc-drawing contacts of that pole of said auxiliary circuit breaker that is traversed by said abnormal current and then to reclose said contacts after a very short interval; means, including a device to retard its operation, and also controlled by said relay to effect the retarded opening of the arc-drawing contacts of said main circuit breaker to efiect the separation of said contacts of the latter if said abnormal current should persist, the arc-drawing contacts of said auxiliary' circuit breaker remaining closed.

4. The combination of a main circuit breaker comprising at least one pole; a circuit to carry a load and controlled by said main circuit breaker; an auxiliary circuit breaker comprising the same number of poles as said main circuit breaker and connected in series ,with the latter; operating means including an ultra-rapid relay in the con-' trolling circuit of each of the poles of said auxiliary circuit breaker; a coil in said controlling circuits to control the opening of the arc-drawing contacts of each of said poles and adapted to be operated by said ultra-rapid relay in case of an abnormal current in said first mentioned circuit for carrying a load, to open the arc-drawing contacts of that pole of said auxiliary circuit breaker that is traversed by said abnormal current and then to reclose said contacts after a very short interval; means of the coil of the controlling circuit of a pole after the arc-drawing contacts of the latter have been opened; means to reclose said circuit of said coil after a suitable interval in order to prevent a second separation of the arc-drawing contacts of said auxiliary circuit breaker should the abnormal current persist; means, including a device to retard its operation, and also controlled by said relay, to effect the retarded opening of the arc-drawing contacts of said main circuit breaker to separate said contacts should the abnormal current thus persist, the arc-drawing contacts of said auxiliary circuit breaker remaining closed.

5. The combination of a main circuit breaker comprising at least one pole; a coil adapted to control the simultaneous opening of the arcdrawing contacts of all of the poles; a circuit to carry a load and controlled by said main circuit breaker; an auxiliary circuit breaker comprising the same number of poles as said main circuit breaker and connected in series with the latter; an overload relay operating in case of simple over-intensity in said first mentioned circuit for carrying a load, to close the circuit of said coil and open the arc-drawing contacts of said main circuit breaker, said auxiliary circuit breaker remaining closed; means operating in case of an abnormal current in said first mentioned circuit for carrying a load, to separate the contacts of that pole or said auxiliary circuit breaker that is traversed by said abnormal-current and then to reclose said contacts after a very short interval; and means operating thereafter, it said abnormal current persists, automatically to separate the contacts of said main circuit breaker, said auxiliary circuit breaker remaining with its contacts closed.

6 The combination of a main circuit breaker comprising at least one pole; a circuit to carry a load, controlled by said main circuit breaker; an

{or cutting the circuit auxiliary circuit breaker comprising the same number of poles as said main circuit breaker and connected in series with the latter; means for ensuring at will the simultaneous closing or opening or the arc-drawing contacts of all of the poles or said main circuit breaker, the arc-drawmg contacts or said auxiliary circuit breaker remaining closed; operating means including an ultra-rapid relay in the controlling circuit of each of the poles of said auxiliary circuit breaker; pneumatic controlling means operatively connected to the arc-drawing means of said auxiliary circuit breaker and including a compressed air intake-valve, opening of which controls the operation of said controlling means, said ultra-rapid relay acting upon said valve in case of an abnormal current in said first mentioned circuit, to

open the arc-drawing'contacts or that pole of said auxiliary circuit breaker traversed by said abnormal current and then to reclose the said contacts after a very short interval; and means operating thereafter, if said abnormal current persists, to separate the arc-drawing contacts of said main circuit breaker, those of said auxiliary circuit breaker remaining closed.

7. The combination or a main circuit breaker comprising at least one pole; a circuit for carrying a load, controlled by said main circuit breaker; an auxiliary circuit breaker comprising the same number or poles as said main circuit breaker and connected in series with the latter; means for ensuring at will the simultaneous closing or opening of the arc-drawing contacts of all of the poles of said main circuit breaker, the arcdrawing contacts or said auxiliary circuit breaker remaining closed; a pneumatic operating mechanism for each pole of said auxiliary circuit breaker; a lever system for operating the movable contact of each pole of said auxiliary circuit breaker, said mechanism being electrically insulated from said lever system; an insulating column operatively connected to said mechanism and to said lever system to transmit the operative movement of said mechanism to said lever system, and comprising several elements, these elements and those of said lever system, which ensure transmission of the movement, being in continuous engagement without any disengagement on the closing and opening or the arc-drawing contacts of said auxiliary circuit breaker; controlling means for said pneumatic operating mechanism and operating in case of an abnormal current in said first mentioned circuit to open the arc-drawing contacts of that pole or said auxiliary circuit breaker that is traversed by said abnormal current and then to reclose said contacts after a very short interval; and means ren- T dered operative thereafter, if said abnormal current persists, to open the arc-drawing contacts of said main circuit breaker, the arc-drawing contacts of said auxiliary circuit breaker remaining closed.

8. The combinati n of a main circuit breaker comprising at least one pole; a circuit to carry a load and controlled by said main circuit breaker; an auxiliary circuit breaker comprising the same number of poles as said main circuit breaker and connected in series with the latter; means for ensuring at will the simultaneous closing or opening of the arc-drawing contacts of all of the poles of said main circuit breaker, the arcdrawmg contacts of said auxiliary circuit breaker remaining closed; pneumatic operating means for each pole of said auxiliary circuit breaker, said means comprising essentially a cylinder, 2

- tacts after a very short interval;

piston in said cylinder and a two-cycle slide-valve gear of which the first cycle, corresponding to the opening of the arc-drawing contacts of said auxiliary circuit breaker, effects the simultaneous closing of the intake and the exhaust of said cylinder on the termination of the opening of said contacts, the second cycle effecting the reclosing of said contacts of said auxiliary circuit breaker; controlling means for said pneumatic operating means, and operative in case oi an abnormal current in said first mentioned circuit, to open thecontacts oi the poleof said auxiliary circuit breaker that is traversed by said abnormal current and then to reclose said contacts after a very short interval; and means rendered operative thereafter, if said abnormal current persists, to open the arc-drawing contacts of said main circuit breaker, the arc-drawing contacts of said auxiliary circuit breaker remaining closed.

9. The combination of a main circuit breaker comprising at least one pole; a circuit for carrying a load, controlled by said main circuit breaker; an auxiliary circuit breaker comprising the same number of poles as said main circuit breaker and connected in series with the latter; means for ensuring at will the simultaneous closing or opening of the arc-drawing contacts of all of the poles of said main circuit breaker, those of said auxiliary circuit breaker remaining closed; pneumatic operating mechanism for each pole oi said auxiliary circuit breaker, comprising essentially a cylinder, a piston in said cylinder and a twocycle slide-valve gear the displacement of which corresponds to the retardation of the reclosing of the contacts of the circuit breaker; mechanical rneans for ensuring said displacement; an ad- Justable device for retarding the reclosing of the contacts, adapted to cooperate with said mechanical means; controlling means for said pneumatic operating mechanism, operative in the case of an abnormal current in said first mentioned circuit, to open the contacts of that pole of said auxiliary circuit breaker that is traversed by said abnormal current and then to reclose said conand means rendered operative thereafter, if said abnormal current persists, to open the contacts of said main circuit breaker, the contacts of said auxiliary circut breaker remaining closed.

10. The combination of a main circuit breaker comprising at least one pole; a circuit to carry a load and controlled by said main circuit breaker; an auxiliary circuit breaker comprising the same number of poles as said main circuit breaker and connected in series with the latter; means for ensuring at will the simultaneous closing or opening of the arc-drawing contacts of all of the poles ofsaid main circuitv breaker, the arc-drawing contacts of said auxiliary circuit breaker remaining closed; pneumatic actuating mechanism for each pole of said auxiliary circuit breaker, comprising essentially a cylinder, a piston in said cylinder and a two-cycle slide-valve gear, the displacement of which corresponds to the retardation of the reclosing of the contacts of the circuit breaker; mechanical means for ensuring said displacement; an adjustable pneumatic device for effecting such retardation, adapted to cooperate with said mechanical means; controlling means for said pneumatic actuating mechanism, operative in case of an abnormal current in said first mentioned circuit, to open the contacts of that pole of said auxiliary circuit breaker that is traversed by said abnormal current and then to reclose said contacts after a very short interval; and means rendered operative thereafter, if said abnormal current persists to openthe contacts of said main circuit breaker, those of said auxiliary circuit breaker remaining closed.

11. The combination of a main circuit breaker comprising at least one pole; a circuit for carrying. a load and'controlled by said ma'in'circuit breaker; an auxiliary circuit breaker comprising the same number of poles as said main circuit breaker and connected in series with the latter; means for ensuring at will the simultaneous closing or opening of the arc-drawing contacts of all-oi the poles of said main circuit breaker, those of said auxiliary circuit breaker remaining closed; pneumatic actuating mechanism for each of the poles of said auxiliary circuit breaker, com.- prising essentially a cylinder, a piston in said cylinder and a slide-valve gear; a spring adapted to be tensioned by the operation or" reclosing aredrawing contacts of said auxiliary circuit breaker and to return said slide-valve .to its initial position after reclosing of said contacts; controlling means for said pneumatic actuating mechanism, operative in case of an abnormal current in said first mentioned circuit, to open the contacts of that pole of said auxiliary circuit breaker that is traversed by said abnormal current and then to reclose said contacts after a very short interval; and means operative if said abnormal current persists to open the contacts of said main circuit breaker, those of said auxiliary, circuit breaker remaining closed.

12. The combination of a main circuit breaker comprising at least one pole; a circuit for carrying a load and controlled by said main circuit breaker; an auxiliary circuit breaker comprising the same number of poles as said main circuit breaker and connected in series with the latter; means for ensuring at will the simultaneous closing or opening of the arc-drawing contacts of all of the poles of said main circuit breaker, the arc-drawing contacts ofsaid auxiliary circuit breaker remaining closed; pneumatic actuating mechanism for each pole of said auxiliary circuit breaker comprising essentially an intakevalve' for compressed air, a cylinder, a piston in said cylinder and a slide-valve gear; means to return said slide valve gear to its initial position upon reclosure of arc-drawing contacts of said auxiliary circuit breaker and closure ofsaid intake-valve; controlling means forsaid pneumatic actuating mechanism, operative in case of an abnormal current in said first mentioned circuit,

to open the arc-drawing contacts of that pole of said auxiliary circuit breaker that is traversed by said abnormal current and then to reclose said contacts after a very short interval; and means operative in case of persistence of said abnormal current, to open the arc-drawing contacts of said maincircuit breaker, those of said auxiliary circuit breaker remaining closed.

13. The combination of a main circuit breaker comprising at least one pole; a circuit for carrying a load and controlled by said main circuit breaker; an auxiliary circuit breaker comprising the same number of poles as said main circuit breaker and'connected in series with the latter;

' means for ensuring at will the closing or opening simultaneously. of thearc-drawing contacts of all the poles of said main circuit breaker, those of said auxiliary circuit breaker remaining closed; an operating system for pneumatically actuating the poles of said auxiliary circuit breaker, comprising compressed air feeding current in said first named circuit, to open the arc-drawing contacts of that pole of said auxiliary circuit breaker that is traversed by said abnormal current and then to reclose said contacts after a very short interval; and means operative in case of persistence of said abnormal current, to open the arc-drawing contacts of said main circuit breaker, those of said auxiliary circuit breaker remaining closed.

14. The combination of a main circuit breaker comprising at least one pole; a circuit'for carrying a load and controlled by said main circuit breaker; an auxiliary circuit breaker comprising the same number of poles as said main circuit breaker and connected in series with the latter; means for ensuring at will the closing or opening simultaneously of the contacts of all the poles of said main circuit breaker, those of said auxiliary circuit breaker remaining closed; a pneumatic operating system for the poles of said auxiliary circuit breaker, comprising compressed air feeding means preferably mounted upon the base of said auxiliary circuit breaker and insulated from the contacts of the latter, pneumatic operating mechanism for the arc-drawing contacts of said auxiliary circuit breaker positioned adjacent to and uninsulated from said contacts, a device for admitting compressed air to said operating mechanism, a hollow insulating column connecting said device with said operating mechanism, the compressed air passing through said column and means for rotating said column about its longitudinal axis; means actuated by rotation of said column to control the operation of said device; controlling means for said pneumatic operating system, operative in case of an abnormal current in said first named circuit, to

open the arc-drawing contacts of that pole of said auxiliary circuit breaker that is traversed by said current and then to reclose said contacts after a very short interval; and means operative if said abnormal current persists, to open the arc-drawing contacts of said main circuit breaker, those of said auxiliary circuit breaker remaining closed.

CHARLES BRESSON. 

